Dorsal spinous process impingement, also known as "Kissing spines", is a condition of the horse's back which can cause significant pain. The dorsal spinous processes (the sections of bone which project upwards from the horse's vertebral column) are interconnected by ligaments (called interspinous ligaments). In the back of a normal horse, these processes are evenly spaced apart from one another. However, if the space between the spinous processes is reduced and they get too close together, they this will cause them to impinge on one another.
The condition may be dynamic, where impingement only occurs when the horse is moving, or static, where impingement occurs even while their at rest and may even become fused. It is this impingement which is what causes the horse pain, which can range from mild to severe. Kissing spines most frequently affects the horse's thoracic vertebrae, which consists of the area from the withers to just behind where the saddle would sit.
Kissing spines usually has a mild to severe impact on the horse's performance and behavior. Behavioral changes are associated with handling on the ground, while ridden, and/or discipline-specific.
How Kissing Spines is Diagnosed
Your veterinarian will likely want to watch your horse while schooled at different gaits. Thermographic imaging may also be a useful aid in diagnosis. Kissing spines is confirmed through radiographs (x-rays) taken of the horse's back from the withers through the lumbar vertebrae. Radiographic changes such as sclerosis, narrowing of interspinous spaces, periosteal reactions, and occasionally cyst-like lesions/radiolucent areas, mainly in the area from T13-18 are observed.
Treatment and Management of Kissing Spines
Your veterinarian's recommended treatment for kissing spines will differ depending on the severity of the condition, amount of pain your horse is in, and the intended use and expectations of the horse. Horses which don't seem to be in much pain and aren't expected to perform athletically may get by with long-term treatment with oral anti-inflammatories (aka bute). Therapies often used to help with the pain include local corticosteroid injections, Tildren, and mesotherapy.
There are several beneficial adjunctive therapies which can help with the pain and muscle spasms, which include acupuncture, chiropractic adjustments, equine message, and shockwave therapy.
For more severe cases where horses show no improvement with medical management, and depending on the expectations for performance level of the horse, your veterinarian may recommend surgery. There are several different surgical procedures available which have shown varying success.
One of the most important aspects of long term management of kissing spines is physical therapy. Physical therapy is aimed at strengthening specific muscles in the back and pelvic areas----M. multifidus (adjacent to the spine), M. psoas (under the spine to the hips), and the abdominal oblique muscles which run along the abdominal wall. Exercises often may involve lots of lunge work, frequently with side reins, using a Pessoa system and belly lifts.